The invention relates to an arrangement of a differential for driving two vehicle wheels, in which a gearbox casing of the differential is rotatably mounted in a non-rotating outer casing and a follower made of a non-metallic material and fixed in its position relative to the outer casing by a holding device can be brought into contact under a small contact pressure with an annular face which is fixed relative to the gearbox casing in terms of movement and is concentric to the bearing axis.
In a known arrangement of this type (German Patent Document DOS 3,034,493), a ring gear fixed to the gearbox casing in terms of rotation and concentric to the bearing axis is subjected to axial bending when loaded by the corresponding driving pinion. In order to limit this bending to a defined degree, a stop fixed on the non-rotating axle casing in which the gearbox casing is rotatably mounted interacts with an annular face of the ring gear. In this known arrangement, the follower acts as a distance piece secured on that end of the stop which faces the annular face, being of such a thickness that it rests against the annular face. The distance piece is composed of a material which is abraded due to the contact with the annular face, with the result that a gap corresponding to the thickness of the distance piece is formed between the end of the stop and the annular face of the ring gear, the end of the stop thereafter preventing axial bending of the ring gear beyond the width of the gap.
Despite a considerable manufacturing effort, running noises associated with the toothing occur again and again at rear-axle gear units of passenger vehicles. A great deal of effort is put into preventing the transmission of these noises into the passenger compartment, e.g. by means of the flexible suspension of the rear-axle gear unit in the axle support, and this may well be disadvantageous as regards costs and occurrence of phenomena on the vehicle such as, for example vibration and juddering.
An object on which the invention is based consists essentially in suppressing the above mentioned running noises associated with the toothing.
Starting from an arrangement of a differential of the type referred to above this object is achieved in an advantageous manner by providing a construction wherein the follower is a solid of revolution made of a noise-deadening material rotating concomitantly freely and positioned to be in continuous contact.
In the arrangement of a differential according to the invention, a solid of revolution coated with damping material or composed of this material is pressed under a small load against the ring gear or the gearbox casing so as to rotate freely with it and thus prevents free vibration in a manner comparable, for instance, to the reduction of the noise level brought about by placing a finger on a bell.
The solid of revolution can be accommodated in a cover plate of the outer casing or accommodated in the casing itself.
The contact pressure of the solid of revolution can be determined exclusively by the elastic properties of its material and by the choice of the installation dimensions and the tolerances or by a spring.
A damping force connected in parallel with the spring can additionally be provided for the purpose of providing contact pressure.
The solid of revolution can act either radially or axially on the ring gear or gearbox casing, in relation to the bearing axis of the gearbox casing.
The annular face interacting with the solid of revolution is preferably kept free of oil by means of an oil scraper.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.